[R-sig-Geo] How to do Zonal Statistics after Kriging in R given Shapefile of Polygon
Jesse Berman
berman.jesse at gmail.com
Thu Sep 12 17:44:15 CEST 2013
Edzer is correct about this. I was just looking at spTransform and adjusted
the data into a Robinson global projection. If you set muni.sp and
brgy_poly to this projection the block kriging now works.
You'll have to adjust your variogram, as it becomes a singular model, but
for demonstration purposes it works. As an aside, you may want to consider
numbers of point pairs when setting your variogram.
robin<-"+proj=robin +lon_0=0 +x_0=0 +y_0=0 +ellps=WGS84 +datum=WGS84
+units=m +no_defs"
muni.sp2<-spTransform(muni.sp, CRS(robin))
brgy_poly2<-spTransform(brgy_poly, CRS(robin))
## Variogram plot
v.obj<-variogram(POVERTY_INCIDENCE~1, locations=coordinates(sp_point),
data=muni.sp2, cloud=F)
## Assuming exponential model
v.exp <- fit.variogram(v.obj,vgm(psill=1, model='Exp', range=1))
## Krige and Plot
kr <- krige(POVERTY_INCIDENCE~1, muni.sp2, newdata=brgy_poly2, model=v.exp)
spplot(kr, "var1.pred", col.regions = rev(topo.colors(20)))
-----
--------------------------------------------------------
Jesse D Berman, PhD
Yale University
School of Forestry and Environmental Studies
Post-Doc Fellow
--
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